package com.yy.utils.ntes;

import java.security.MessageDigest;
/**
 * 直播校验
 * @author yy 
 * @date 2017-04-06 14:39:47
 */
public class CheckSumBuilder {
	/**
	 * 
	 * @param appSecret 3398ae1eea74
	 * @param nonce 	随机数
	 * @param curTime	当前UTC时间戳
     * @return String
	 */
    public static String getCheckSum(String appSecret, String nonce, String curTime) {
        return encode("sha1", appSecret + nonce + curTime);
    }
    
    private static String encode(String algorithm, String value) {
        if (value == null) {
            return null;
        }
        try {
            MessageDigest messageDigest = MessageDigest.getInstance(algorithm);
            messageDigest.update(value.getBytes());
            return getFormattedText(messageDigest.digest());
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }
    
    private static String getFormattedText(byte[] bytes) {
        int len = bytes.length;
        StringBuilder buf = new StringBuilder(len * 2);
        for (int j = 0; j < len; j++) {
            buf.append(HEX_DIGITS[(bytes[j] >> 4) & 0x0f]);
            buf.append(HEX_DIGITS[bytes[j] & 0x0f]);
        }
        return buf.toString();
    }
    
    private static final char[] HEX_DIGITS = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
}